This invention relates to polymeric coatings and sealants to inhibit corrosion and ice formation on substrates, especially the faying surfaces of a substrate. The invention further relates to compositions and methods of making and applying a polysiloxane-containing composition resistant to corrosion and ice formation or sealant on a faying surface of a substrate.
The everyday build-up of ice upon the surfaces of mechanical, physical, and natural objects is a familiar annoyance, and quite often a safety hazard. The slick layers of ice that form on highways, driveways, and walkways make transportation difficult. The masses of ice that accumulate within or upon industrial, agricultural, or other mechanical equipment make operation of the equipment difficult or impossible. And, the weight of ice that weighs upon power lines, buildings, and signs often causes damage to those structures.
Build-up of ice upon the wings and components of an aircraft is of particular concern. The lift generated by the wings, and thus the ability of the aircraft to become and remain airborne, is dependent on the shape of the wings. Even a small accumulation of ice upon the surface of the wings can have a huge aerodynamic effect and can dramatically reduce the ability of the wings to lift the aircraft into the air. Further, ice build-up along control surfaces of the aircraft can impede the movement of those surfaces and prevent proper control of the aircraft.
There are a large variety of techniques used to control the build-up of ice upon the wings and other surfaces of aircraft. For instance, the aircraft may be de-iced before takeoff by application of a chemical spray, which melts the ice from the wings. Such deicing sprays are often toxic and harmful to the environment. The ritual of de-icing is well known to airline passengers traveling through cold environments.
Another method of de-icing aircraft includes providing flexible pneumatic coverings along the leading edges of the wings, and supplying bursts of air or fluid to the wing through the flexible coverings to break away any overlying ice. Similarly, bleeding air from the aircraft engine and routing the heated air to the surface of the wing heats the wing and melts the ice. Finally, ice may be removed from the wing by providing high-current pulses of electricity to a solenoid disposed within the wing that causes the wing to vibrate, fracturing any accumulated ice.
Although the previously mentioned methods of ice removal are generally effective, they require the continuous supply of air, chemicals, or electrical power in order to rid the wing of its burden. It would be preferred, of course, to prevent the accumulation of ice in the first place, but past attempts to develop practical passive methods of ice prevention have failed, along with efforts to reduce moisture penetration, i.e. poor barrier to moisture penetration.
One would expect that known non-stick coatings would be able to prevent ice from adhering to coated surfaces. In fact, aluminum surfaces coated with a Teflon(trademark) material exhibit a zero break force between the ice and the Teflon(trademark) coating. However, upon repeated freezing, the favorable properties exhibited by Teflon(trademark) and similar coatings degrade, resulting in a coating with little or no anti-icing capability.
In addition, there exists a need for an improved approach for the protection of the faying surfaces of aluminum-alloy, aircraft structural components such as wing and fuselage skin panels, stiffeners (which include but are not limited to spars, ribs, stringers, longerons, frames, shear clips, xe2x80x9cbutterflyxe2x80x9d clips, etc.), hinges, doors, etc., and the mechanical components attached to these aforementioned components. Furthermore, there exists a need for improving the delivery methods and systems of such coatings onto the aluminum-alloy, aircraft structural components, including relatively large, surface-area components. Commonly assigned U.S. Pat. No. 6,475,610 discloses such methods and useful coatings for improving the corrosion protection of faying surfaces, and is incorporated by reference herein as if made a part of this present application.
What is needed is a durable surface coating, with long lasting anti-icing properties delivered to coat and protect surfaces, including faying surfaces. What is further needed is a surface coating with anti-icing properties that may be easily applied to the faying surfaces of an aircraft as well as an effective moisture barrier.
The present invention is directed to a method for applying to a substrate having a faying surface, a polysiloxane-containing coating, preferably a polysiloxane(amide-ureide) coating capable of inhibiting corrosion as well as the accumulation of ice. One embodiment of the present invention is directed to a polysiloxane(amide-ureide) that forms a durable, long lasting, anti-corrosive and anti-ice coating when directed to a substrate faying surface.
Further, the present invention is directed to a substrate having a faying surface coated by a coating made from a material comprising a polymer formed from a combination of two components:xe2x80x94(Component A)-(Component B)xe2x80x94 wherein Component A is represented by the formula shown in (Ia): 
and Component B is represented by either structure, as shown in (Ib) or (Ic): 
where X is a prepolymer, shown in formula (Id): 
wherein R1, R3, and R4 are independently selected from the group consisting of hydrogen; C1 to C6 alkyls and aryls; C3 to C6 cycloaliphatics; and C3 to C6 heterocycles;
A1 and A2 are independently selected from the group consisting of C1 to C6 alkyls and aryls; C7 to C12 alkylaryls; C3 to C6 cycloaliphatics; and C3 to C6 heterocycles; and are preferably methyl;
R2, R5, and R6 are independently selected from the group consisting of C1 to C10 alkyls; aryls, and heterocycles;
wherein the alkyls may be linear or branched, saturated or unsaturated, halogenated or non-halogenated; aryls may be halogenated or non-halogenated; cycloaliphatics may be saturated or unsaturated, halogenated or non-halogenated; heterocycles may be saturated or unsaturated, halogenated or non-halogenated; and alkyaryls may be linear or branched, saturated or unsaturated, halogenated or non-halogenated;
x is a number from 1 to about 10,000, preferably from 1 to about 1000, and most preferably between about 20 and about 200; and, to result in an amine-terminated polysiloxane (amide-ureide), as shown in formula (Ie):
[X]-CYAN-[X]xe2x80x83xe2x80x83(Ie)
where X is as shown in (Id), CYAN is a diisocyanate residue from the group of alkyl diisocyanate with the alkyl portion being from C1 to C10 and non-linear aryl diisocyanate or non-linear heterocyclic diisocyanate, and Z is a residue of a dicarboxylic acid wherein the hydroxyl from each carboxylic acid component has been replaced with a halide constituent, typically chloride. At least a portion of the substituted dicarboxylic acids is selected from fumaryl, succinyl, phthalyl, terephthalyl, and maleiyl halides, and more preferably fumaryl chlorides and maleiyl chlorides. Subsequently, the moiety (Ie) is reacted with an olefinic acid halide, generally represented by the formula shown in (If), as: 
where R3 is as defined above, and R5 is aliphatic, aryl; C3 to C6 cycloaliphatic; and C3 to C6 heterocyclic; wherein the alkyls may be linear or branched, saturated or unsaturated, halogenated on non-halogenated; aryls may be halogenated or non-halogenated; cycloaliphatics may be saturated or unsaturated, halogenated or non-halogenated; heterocycles may be saturated or unsaturated, halogenated or non-halogenated; and alkyaryls may be linear or branched, saturated or unsaturated, halogenated or non-halogenated; where n is 0 to 10.